Method of treating leather board



June 21, 1938.

J. F. POLLARD METHOD OF TREATING LEATHER BOARD Filed April 15, 1936 INVENTOR Patented June 21, 1938 UNITED STATES PATENT OFFICE by mesne assignments,

to The International Leather Oompany; Boston, Man, a corporation of Maine Application April 15, 1938, Serial No. 14.495 9 Claims. (CL 8-107) This invention relates to a vari-colored leather board product and method of producing the same and has particularly to do with providing an improved and novel process employed in the manus iacture oi heels ior shoes. Heretofore it has been proposed to make a vari-colored or striped product by staining one or both flat faces oi leather board with a coloring liquid, such as paint or lacquer, which penetrates but partially the thickness oi the leather board, as disclosed in Patent No. 1,844,366 to Walter P. Rankin. The present invention may be employed with or without coloring material to produce a varl-colored or vari-shaded striped board, that is, it may be employed either in conjunction with the process generally and broadly disclosed in said Rankin patent, or without the employment of any added coloring material to produce the vari-colored or vari-shaded product of this invention.

Also, it has heretofore been proposed to bleach or treat the flat side suriaces of leather board with aqueous solutions oi acids which are not only oiiensive. but actually injurious to the workmen engaged in the treatment therewith of leather board ior heeling purposes. Moreover, such acids tend to iniuriously aiiect the "utility oi the leather board so treated. particulain to render it more brittle.

The present invention provides a superior product and process and not only obviates the necessity and disadvantages oi using such acids, but also'may be practiced more cheaply and. moreover, produce a materially better product more closely approaching the characteristics oi genuine leather. particularly in that it is more flexible, ilrmer. tougher and more resistant to abrasion than leather board which has been subjected to treatment, particularly acid treatment, as heretoiore proposed and practiced.

In the practice oi the process of this invention there preferably is provided a leather board made irom colored stock so that the resultant leather board made in the paper making process is colored through and through to substantially the same color, for example, to a reddish or an orange color as distinguished irom the ordinary gray board, though the latter may be employed and treated in substantially the same manner. In accordance with thepreferred practice of this invention, in order to change the color and/or shade oi the leather board. said board is then subjected to treatment with an aqueous solution of sodium bi-iluoride by dipping orpainting the board with the said solution, the concentration of which is preferably thatobtained by mixing iour to six ounces oi powdered sodium lei-fluoride in a gallon of water. The solution thus obtained is not only substantially odorless and inoil'ensive, but 'also entirely harmless to workers coming in contact with the same. Moreover, the cost of 5 the solution is substantially less than is the case with treatments in use heretofore. If desired, though it is not necessary, color, for example yellow and/or orange aniline acid dye, may be added to the sodium bi-ilv ride solution in the 10 amount oi to ounce of dye per gallon, and it is iound that the sodium bi-fluoride assists in the penetration and/or setting of the dye. A typical example oi the solution is as follows:-

Sodium bi-iiuoride "ounces-.. 4 w e Azo yellow dye do y. Orange Y, Colour Index No. 15i ..do Y, water irnllnn 1 The solution thus made up is then preferably 20 heated to a temperature of -125 F. and is then ready for use and may be applied to the board by dipping or painting, as desired, dependent somewhat upon whether one or both sides oi the board are to be treated. Ordinarily 25 the depth oi penetration desired is of the order oi A to oi an inch and, it is iound in practice, for example. that leather board three sixteenths oi an inch thick may be suitably treated ior a period of one and one-hali to two and one-hali 30 minutes in the solution as just described and. upon drying, thus assume the desirable and superior physical characteristics before referred to. and provide a lighter colored or shaded portion wherever treated. From such sheet material 5 vbich presents an edge-stripe at its out section there may be cut heel liits having an outside suriace or surfaces thereof oi a color or shade contrasting with that oi the darker center portion of the'board. Ii desired to lighten the color 40 and/or shade to a desired depth of the board throughout its thickness, the penetration may be carried entirely through the board and may be very quickly accomplished. particularly when no dye is employed in the solution.

The accompanyinl drawing illustrates heel liits as one example of a product oi the process hereinbeiore described. In said drawing. Fisure 1 is a perspective view oi a portion oi a sheet oi leather board before treatment. Fig. 2 is a per- 50 spective view oi a heel liit cut irom board that has been treated throughout its thickness, and Fig. 3 is a perspective view of a heel liit cut irom board that has been treated in a manner to present three transverse stripes on its out section.

The illustration of the untreated board i 0 (Fig. 1) shows a dark edge face it, as would appear at a cut section of untreated board, for comparison with the much lighter color or shade of the edge face I of the lift I! (Fig. 2) which has been cut from board left in the solution long enough to efiect a through and through penetration. The lift 20 (Fig. 3) is cut from board previously dipped in the solution for a briefer period of time and presents at its edge face a central stripe 2i and two outer or marginal stripes 22 and 23. The two outer stripes, representing the treated board stock, are here shown as of a lighter color or shade than the central stripe which represents the untreated board stock. Obviously a heel lift or other product having a two-stripe edge face may be produced by painting only one side face of the board, the penetration of the solution partly through the board from that face only leaving the remainder of its thickness of the color of the fibres as originally processed to make the leather board.

In lieu of the sodium bi-fiuoride herein referred to, there may be employed potassium bifluoride, ammonium bi-fiuoride, or a combination of said bi-fiuorides, namely the alkali metal acid salts pf hydrofluoric acid and the ammonium acid salt of hydrofluoric acid.

Having described my invention what I wish to claim and secure by Letters Patent is:-

l. The method of making a striped leather board product which consists in first providing a leather board of uniform color throughout, then treating the said leather board through only a porticn of its thickness with an aqueous solution comprising at least one acid salt selected from the group consisting of the alkali metal acid salts of hydrofluoric acid and the ammonium acid salt of hydrofluoric acid, and finally drying the same.

2. The method of making a striped leather board product which consists in first providing a leather board of uniform color throughout. then treating the said leather board through only a portion of its thickness with an aqueous solution comprising a coloring material and at least one acid salt selected from the group consisting of the alkali metal acid salts of hydrofluoric acid and the ammonium acid salt of hydrofluoric acid, and finally drying the same.

8. The method of making a leather board product which consists in first providing a leather board of uniform color throughout, then treating the said leather board to a substantial depth with an aqueous solution comprising at least one acid salt selected from the group consisting of the alkali metal acid salts of hydrofluoric acid and the ammonium acid salt of hydrofluoric acid, and finally drying the same.

4. The method of making a striped leather board product which consists in first providing a colored leather board of uniform color throughout and then treating the said leather board through only a portion of its thickness with an aqueous solution of sodium bi-fluoride, and finally drying the same.

5. The method of making a striped leather board product which consists in first providing a leather board of uniform color throughout and then treating the said leather board through only a portion .of its thickness with an aqueous solution comprising aniline dye and at least one acid 'salt selected from the group consisting of the alkali metal acid salts of hydrofluoric acid and the ammonium acid salt of hydrofluoric acid, and finally drying the same.

6. The method of making a striped leather board product which consists in first providing a leather board, then treating said leather board through only a portion of its thickness with an aqueous solution of sodium bi-fluoride, and then drying the same.

7, The method of making a leather board product which consists in first providing a leather board, then treating said leather boar'l throughout its thickness with an aqueous solution of sodium bi-fiuoride, and then drying the same.

8. The method of making a leather board product which consists in first providing a leather board, then treating said leather board throughout its thickness with an aqueous solution comprising at least one acid salt selected from the group consisting of sodium bi-fiuoride. potassium bi-fiuoride and ammonium bi-iluorlde. and then drying the same.

9. The method of making a leather board product which consists in first providing a leather board. then treating said leather board through only a portion of its thickness with an aqueous solution comprising at least one acid salt selected from the group "consisting of sodium bi-fiuorlde, potassium bi-fiuoride and ammonium bi-i'iuoride, and then drying the same.

' JOSEPH I". POLLARD.

CERTIFICATE OF CORRECTION Patent No. 2,121,668-

June a JOSEPH F. POLLARD.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line i l, strike out the words "to a desired depth" and insert the same after "shade" in 1ine-58; and that the'said Letters Patent should be read with this correction therein that t of the case in the Patent Office.

.Eiiigned and sealed this 26th dayof July, A. D. 1938.

(Seal) Henry Van Arsdale he same may conform to the record Acting commissioner of Patents. 

